Self-heating/cooling container

ABSTRACT

A self-heating or self-cooling container, which uses a chemical reaction to effect heating or cooling. The reagents for the chemical reaction are stored separately in two sealed compartments ( 5, 6 ) having a common dividing wall ( 7 ), which can move within the compartments to expand the volume of one compartment at the expense of the other compartment. This arrangement allows efficient use of space within the reaction module of the can, which is particularly important where large amounts of reagent are required to obtain the necessary heating or cooling effect and where the products of the chemical reaction occupy a significantly increased volume compared to the initial reagent in the compartment.

The present invention relates generally to self-heating or self-coolingcontainers, which effect heating or cooling using an exothermic orendothermic chemical reaction respectively. Such containers usually haveat least two compartments to hold the reagents for the chemicalreaction, separately, in an inert state. When heating or cooling isrequired, the reagents are mixed and an exothermic or endothermicreaction occurs. In particular, the present invention concerns anarrangement, which is designed to optimise the volume of the containeroccupied by the reagents for the chemical reaction.

Many such self-heating/self-cooling containers have been suggested inthe prior art. However, in the containers according to the prior art asignificant volume of the container is taken up by the chemicalreagents, which have to be held separately (in sealed compartments),prior to activation of the reaction. Usually, one of the reagents is fedinto the compartment containing the other reagent, when the reaction isinitiated, leaving it's own compartment empty. This empty compartmentthen effectively becomes “dead” or wasted space.

In addition, during some reactions, the products formed during thereaction occupy a larger volume than the original reagent, therebycausing an increase in pressure within the reaction chamber, which hasto be released, either by destroying part of the reaction chamber or bysome pressure release means. This is true of the popular exothermicreaction suggested in much of the prior art for self-heating cans,lime+water. This exothermic reaction is popular, because the reagentsare low cost and both the reagents and products of the reaction arerelatively harmless. A problem with this reaction is that a relativelylarge volume of lime is required to obtain the necessary heat outputfrom the reaction. Furthermore, on addition of the water to the lime,the lime can swell by as much as 40%, thereby occupying an even largervolume. This means that a self-heating container using this exothermicreaction has to be relatively large and the proportion of the containeroccupied by the product is relatively small.

In such containers, the reaction chamber is filled with lime and uponactivation of the can by a user, water is fed into the reaction chamberwhere it reacts with the lime to form a product, which occupies a largervolume than the original lime. Thus, either the pressure in the reactionchamber increases, making the container dangerous to handle or part ofreaction chamber has to rupture in order to relieve the pressure in thechamber.

In the present invention, the reaction module of the container has twocompartments, having a common, moveable wall. Thus, as one of thereagents is expelled from its compartment (the reservoir) into the othercompartment (the reaction chamber) the reaction chamber may absorb thevolume vacated by the expelled reagent by movement of the common wall.Thus, the volumes of the reservoir and the reaction chamber may beoptimised to take up as little volume as possible, because any increasein volume required by the reaction chamber as a result of the chemicalreaction, can be recovered from the volume vacated by the reagent in thereservoir. This arrangement means that the volume occupied by thereaction vessel may be minimised, allowing more room for the product tobe heated or cooled.

Accordingly, the present invention provides a container adapted toself-heat or self cool, the container comprising a first compartment forholding the product to be heated or cooled, a reaction chamber forholding a first reagent, and a reservoir for holding a second reagent,wherein the first and second reagents are chosen such that upon mixingan exothermic or endothermic chemical reaction occurs to effect heatingor cooling of the product respectively, characterised in that thereaction chamber and the reservoir have a common dividing wall, which isadapted to move, to increase the volume of the reaction chamber, whilstdecreasing the volume of the reservoir.

Such containers usually comprise a body and some form of actuationmeans, either in the form of a push-button or a rotateable base section.Upon actuation of the container, a flow path is created between thecompartments containing the first and second reagents and the chemicalreaction is thereby initiated. As the reagent in the reservoir is usedup, the common dividing wall between the reaction chamber and thereservoir can move, increasing the volume of the reaction chamber at theexpense of the reservoir. This allows the reaction chamber toaccommodate any increase in volume occupied by the products of thechemical reaction. Furthermore, the “dead space” which would normallyarise in the reservoir is reallocated to the reaction chamber andtherefore remains in use.

In a preferred embodiment of the invention, the container comprises abody section and a base section, adapted to rotate relative to oneanother. The base section is coupled to the common dividing wall by ascrew thread arrangement. The user of the can initiates the chemicalreaction by turning the base of the can relative to the body. This inturn, moves the common dividing wall to reduce the volume of thereservoir whilst increasing the volume of the reaction chamber.Preferably, the reduction in volume of the reservoir, drives the reagentheld therein into the reaction chamber, activating and feeding thechemical reaction.

Advantageously, the volumes of the reaction chamber and the reservoirare chosen such that as the reagent from the reservoir is expelled intothe reaction chamber, the products produced by the chemical reactionexpand, moving the common dividing wall and thereby reducing the volumeof the reservoir. This in turn forces more reagent from the reservoirinto the reaction chamber. Thus, the reaction becomes self-fuelling.

The invention will now be described, by way of example only, withreference to the accompanying drawing, in which:

FIG. 1 shows a side section view through a self-heating can according tothe invention having a screw thread arrangement to move the commondividing wall between the reservoir and the reaction chamber.

Referring to FIG. 1, a self-heating can 1 comprises a body 2 and a base3, which is rotateable relative to the body 2. An insert 4, is seamed tothe open end of the body 2 and, together with the base, defines areaction chamber 5 for a first reagent (e.g. lime) and a reservoir 6 fora second reagent (e.g. water). A common dividing wall 7 is providedbetween the reaction chamber 5 and the reservoir 6. The periphery of thedividing wall 71 is attached to the insert 4 via a flexible diaphragm72, which accommodates the movement of the common dividing wall 7. Thebase 3 and dividing wall 7 are provided with mutually co-operating screwthreads 35, 75. A flow path 8 is defined, through the centre of thescrew threads 35, 75 between the reservoir 6 and the reaction chamber 5.The flow path 8 is normally closed by a valve 9, which opens in responseto increased pressure within the reservoir.

In use, a user rotates the base 3 of the can 1 relative to the body 2.The base thread 35, is coupled to the base and rotates therewith.However, the dividing wall screw thread is provided as part of thedividing wall, which is anchored to the insert 4, which is itselfanchored to the body 2 and therefore cannot rotate. Thus, the dividingwall screw thread progresses along the base thread and thereby moves thedividing wall axially within the reaction chamber 5/reservoir 6. Thismovement is accommodated by the flexible diaphragm 72, which unrolls. Byuse of this arrangement, the reaction chamber 5 increases in volume atthe same time as the reservoir 6 decreases in volume.

To take the specific, exothermic reaction of lime+water. The reactionchamber 5 is filled with dry lime and the reservoir 6 is filled or atleast partly filled with water. A user activates the exothermicreaction, by twisting the base 3 of the can. This in turn moves thedividing wall 7, reducing the volume of the reservoir 6. This volumereduction pressurises the water in the reservoir 6, which opens thevalve 9, to allow the water into the reaction chamber 5. As the usercontinues to rotate the base 3, more water is transferred from thereservoir 6 into the reaction chamber 5. At the same time, the volume ofthe reaction chamber 5 is increased into the space previously occupiedby the water in the reservoir 6. Thus, the reaction chamber can nowaccommodate the expansion of the lime, without destroying the dividingwall 7 between the reservoir 6 and the reaction chamber 5.

This can arrangement is particularly efficient because the space vacatedby the second reagent is not wasted but instead is used to accommodateany expansion of the reaction products.

Many other methods of actuating the common dividing wall will beapparent to those skilled in the art, as well as different ways ofcollapsing the volume occupied by the reservoir. For example, thereservoir may be provided as a pouch, which naturally collapses once thecontents thereof is expelled.

1. A container adapted to self-heat or self cool the containercomprising: a first compartment for holding a product to be heated orcooled, a reaction chamber for holding a first reagent, a reservoir forholding a second reagent, and an unbreakable barrier wall between thereaction chamber and the reservoir that is adapted to separate the firstreagent from the second reagent and is adapted to move to increasevolume of the reaction chamber and decrease volume of the reservoir,wherein the first and second reagents are chosen such that upon mixingan exothermic or endothermic chemical reaction occurs to effect heatingor cooling of the product, respectively.
 2. A container according toclaim 1, wherein the container further comprises a body and an actuatorarranged to move relative to one another such that movement of theactuator relative to the body opens a flow path between the reservoirand the reaction chamber thereby allowing the second reagent to mix withthe first reagent.
 3. A container according to claim 2, wherein theactuator is adapted to rotate relative to the body.
 4. A containeraccording to claim 2, wherein the actuator is coupled to the commonunbreakable barrier wall, and movement of the actuator relative to thebody moves the unbreakable baffler wall relative to the reaction chamberand the reservoir.
 5. A container according to claim 4, wherein theactuator and the common unbreakable barrier wall are connected by amutually co-operating screw thread anangement and the screw threadanangement drives the movement of the common unbreakable barrier wall.6. A container according to claim 4, wherein the movement of the commonunbreakable barrier wall forces the second reagent from the reservoirinto the reaction chamber.
 7. A container according claim 4, wherein thereservoir and the reaction chamber are connected by a normally closedflow path, which is opened upon movement of the actuator relative to thebody.
 8. A container according to claim 7, wherein the flow path isnormally closed by a valve, which opens in response to movement of theactuator.
 9. A container according to claim 2, wherein the actuatorinitiates the chemical reaction and thereafter expansion of the reactionproducts in the reaction chamber moves the common unbreakable barrierwall, reducing the volume of the reservoir and thereby forcing more ofthe second reagent into the reaction chamber.
 10. A container accordingto claim 2, wherein the actuator is coupled to the unbreakable barrierwall, and movement of the actuator via rotation relative to the bodymoves the unbreakable baffler wall relative to the reaction chamber andthe reservoir.
 11. A container according to claim 10, wherein theactuator and the common unbreakable barrier wall are connected by amutually co-operating screw thread arrangement and the screw threadarrangement drives the movement of the unbreakable barrier wall.
 12. Acontainer according to claim 11, wherein the movement of the unbreakablebarrier wall forces the second reagent from the reservoir into thereaction chamber.
 13. A container according to claim 12, wherein thereservoir and the reaction chamber are connected by a normally closedflow path, which is opened upon movement of the actuator relative to thebody.
 14. A container according to claim 13, wherein the flow path isnormally closed by a valve, which opens in response to movement of theactuator.